This invention relates generally to the regeneration of hydrocarbon conversion catalysts in the presence of a halogen-containing material.
Numerous hydrocarbon conversion processes are widely used to alter the structure or properties of hydrocarbon streams. Such processes include isomerization from straight chain paraffinic or olefinic hydrocarbons to more highly branched hydrocarbons, dehydrogenation for producing olefinic or aromatic compounds, reforming to produce aromatics and motor fuels, alkylation to produce commodity chemicals and motor fuels, transalkylation, and others.
Many such processes use catalysts to promote hydrocarbon conversion reactions. These catalysts tend to deactivate for a variety of reasons, including the deposition of carbonaceous material or coke upon the catalyst, sintering or agglomeration or poisoning of catalytic metals on the catalyst, and/or loss of catalytic metal promoters such as halogens. Consequently, these catalysts are typically reactivated in a process called regeneration. Reactivation can thus include, for example, removing coke from the catalyst by burning, redispersing catalytic metals such as platinum on the catalyst, oxidizing such catalytic metals, reducing such catalytic metals, replenishing catalytic promoters such as chloride on the catalyst, and drying the catalyst.
One of the problems during regeneration of halogen-containing catalysts is loss of halogen itself from the catalyst. This happens when the catalysts are contacted with gases that, while regenerating the catalyst, tend also to remove halogen from the catalyst.
U.S. Pat. No. 5,965,473 discloses a method for recovering chlorine-containing materials from the effluent gases during catalyst regeneration in a hydrocarbon conversion process with a cyclic regeneration operation. To prevent loss of chlorine-containing materials, U.S. Pat. No. 5,965,473 uses one of the off-stream catalyst beds. This is an inefficient use of the vessel that contains the off-stream catalyst bed as well as of the catalyst itself, both of which could be better used for promoting hydrocarbon conversion reactions. Therefore, more efficient methods are sought to decrease the loss of halogen during halogen-containing catalyst regeneration.
This invention is a catalyst regeneration process that uses a bed of adsorbent zone first to adsorb halogen-containing materials that are removed from catalyst undergoing regeneration, and then to desorb these halogen-containing materials so they are re-adsorbed on to catalyst that is undergoing regeneration. The bed of adsorbent, therefore, is contacted with streams and/or at conditions that are different from those used during hydrocarbon conversion. This invention does not use a reaction vessel and its catalyst to adsorb and desorb the halogen-containing materials.
One object of this invention is to improve processes for regeneration of hydrocarbon conversion halogen-containing catalysts. Another object is to recover halogen-containing materials that are present during catalyst regeneration. A third object is to improve the utilization of equipment and catalysts used in hydrocarbon conversion processes, including reforming, isomerization, and dehydrogenation. A fourth object is to improve the efficiency of cyclic catalyst regeneration processes.
In a broad embodiment, this invention is a process for the regeneration of a hydrocarbon conversion catalyst in the presence of a halogen-containing material. The process comprises contacting a regeneration inlet stream comprising a first component selected from the group consisting of oxygen, hydrogen, nitrogen, and a C1-C5 hydrocarbon with a catalyst in the presence of a halogen-containing material at regeneration conditions to at least partially regenerate the catalyst and produce a regeneration effluent stream comprising the material and the first component; contacting a first portion of the regeneration effluent stream with an adsorbent, adsorbing the material on the adsorbent at adsorption conditions, and recovering an adsorption effluent stream comprising the first component and having a reduced concentration of the material relative to the first portion of the regeneration effluent stream; contacting a desorption inlet stream comprising a second component selected from the group consisting of oxygen, hydrogen, nitrogen, and a C1-C5 hydrocarbon with the adsorbent, the adsorbent having the material adsorbed thereon, desorbing the material from the adsorbent at desorption conditions, and recovering a desorption effluent stream comprising the material and the second component; and, forming the regeneration inlet stream from a second portion of the regeneration effluent stream and at least a portion of the desorption effluent stream.
Other embodiments and objects are described in the detailed description of the invention.
U.S. Pat. No. 5,336,834 (Zarchy et al.) discloses an adsorption zone in combination with a catalytic hydrocarbon conversion process that keeps chlorine-containing compounds in the catalyst bed and prevents contamination of product streams with chlorine-containing compounds. The contents of U.S. Pat. No. 5,336,834 are hereby incorporated herein by reference.
U.S. Pat. No. 5,965,473 (Sechrist et al.) discloses a method for recovering chlorine-containing materials from the effluent gases during catalyst regeneration in a hydrocarbon conversion process with a cyclic regeneration operation. The contents of U.S. Pat. No. 5,965,473 are hereby incorporated herein by reference.
U.S. Pat. No. 6,117,809 (Sechrist et al.) discloses a method for recovering chlorine-containing materials removed from a chloride-containing catalyst undergoing reduction by using a sorption zone which contains catalyst. The contents of U.S. Pat. No. 6,117,809 are hereby incorporated herein by reference.